No child is the same, teachers need to recognise this diversity

Any parent with more than one child knows that they don't come out of the womb as blank slates. "They're like chalk and cheese" is a common refrain, emphasising the innate differences between children and how refractory their individual natures are to parental influences. Teachers, too, are well aware of differences in their young charges - in their personalities, their interests, and their aptitudes.
If we think about human nature in general - the range of behavioural tendencies and capacities that characterise us as a species - it becomes obvious that this must somehow be encoded in our DNA.  When it comes to the human brain, this gets much more complex. The details aren't important here - what's important is that variation in the sequence of DNA that comprises all those genes can affect the outcome. Pretty much any psychological trait can be measured and compared between people - including cognitive traits like intelligence, memory, or quantitative reasoning, or personality traits like extraversion, neuroticism, or conscientiousness - people who are more closely related to each other are more similar for those measures.
Our stories, as individuals, do not start with a blank page. But of course, they also do not end with the first page or the first chapter. Nature and nurture are typically set in opposition to each other but, in reality, there is an intimate interplay between them. Humans - especially young children - are learning machines. Our protracted period of development and maturation gives us the opportunity to learn from our experiences and adapt our behaviour accordingly. Given that, you might expect that experience would tend to flatten out or override our innate predispositions.
There are several important reasons for this. First, our experiences do not just happen to us -  they are also influenced by our genetics. In particular, if personality traits are shared between parents and children, this interaction may amplify the traits of the child.
In addition, young children with different temperaments evoke different responses and reactions from their parents, peers, teachers, coaches, and so on which can similarly influence their development. A naturally gifted child - academically, musically, athletically - is likely to receive encouragement from parents and teachers in ways that can lead to a virtuous cycle of increased practice, achievement, praise, and motivation.
As we mature, we become more and more active, autonomous agents who increasingly select our own experiences. An outgoing child will choose to socialise more and develop more expertise in social skills, while a naturally shy child may lag behind in these skills, due to lack of practice. A child with dyslexia, for whom reading is effortful, will naturally tend to read less and fall farther and farther behind their peers without adequate specialised instruction.
Finally, we learn from reward or punishment - from things feeling good or bad. However, the neural circuits that mediate signals of reward or punishment, or that control what kinds of things we pay attention to or find salient, also differ between people. This means that even when two people are exposed to what looks objectively like the same environment or circumstances, their subjective experiences may be highly different. And it is the subjective experience that determines whether we learn from something and how it shapes our future behaviour.
For educators, recognising this diversity is crucially important. It can, in the first instance, lead to greater acceptance of the range of behaviours, abilities, aptitudes, and interests that individuals will present in a classroom. And it can help identify children who may benefit from intervention to counteract the vicious cycles that can amplify initial difficulties if left unchecked. 
-Psychology Today
Kevin Mitchell is an associate professor of genetics and neuroscience at Trinity College Dublin, Ireland